π-Conjugation extension and defects introduction into g-C3N4 by phenanthroline molecular doping to form a metal-free electrochemical sensor towards effective 4-Nitrophenol detection

Abstract

Electrochemical analysis using specifically designed electrodes represents a promising strategy to detect organic pollutants, such as 4-nitrophenol (4-NP), in the environment. Towards this goal, a metal-free composite of phenanthroline doped graphitic carbon nitride (g-C3N4-PD) was synthesized, characterized, and applied as the electrode materials for electrochemical detection of 4-NP in water. The phenanthroline doping simultaneously extends the π-conjugation system of g-C3N4, and creates defect sites in g-C3N4, leading to better conductivity, higher 4-NP adsorption, and significantly enhanced electrocatalytic activity. Electrochemical sensors were fabricated by using g-C3N4-PD-modified carbon electrode. They showed a broad detection concentration range of 2.854–1117 μM and a low detection limit of 39 nM for 4-NP, with high reproducibility, stability and selectivity. Reliable and accurate measurements of 4-NP in real-life water samples have been demonstrated using these electrodes.